Axial flux induction motor or generator

ABSTRACT

An axial flux induction machine includes at least two stators and one rotor where the stators include an inner and outer ring of coils. The stator includes two mirrored structures constructed such as to secure wire coils, amplify magnetic characteristics, and provide a structure upon which to secure a rotary shaft. The structures supporting the outer ring of coils can be in contact between the two stators and the outer ring can be spaced further from the rotary shaft than the inner ring of coils and also further from the rotary shaft than an outer edge of the rotor.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to an axial flux inductionmachine, specifically to an electric motor or generator thatcharacterizes high performance through a more efficient magneticcircuit.

DESCRIPTION OF RELATED ART

The term “motor,” used here, references any type of electrical machinecapable of converting electrical energy to mechanical energy throughmagnetic interactions producing rotary motion on a shaft.

The term “generator,” used here, references any type of electricalmachine capable of converting mechanical energy to electrical energythrough magnetic interactions produced by the rotary motion of a shaft.

An induction motor operates upon both Faraday's Law of Induction andLenz's Law. A conductor experiencing a change in magnetic flux has acurrent induced therein. This induced current will produce a magneticfield, for instance, around the conductor as shown in FIG. 1. Within aninduction motor, conductor coils are placed around a stationary bodyoften comprised of high permeability magnetic material. This body andcoil assembly are referred to as the stator of the motor. The statorcoils of an induction motor are placed such as to produce a rotatingmagnetic field (RMF). This is achieved by separating the coils by 360/n,where n is the number of coil sets. The number of coil sets, n, shouldbe a multiple of the phases. For example, in a three phase motorcomprised of three coil sets, each coil set is offset by 120 degrees.The RMF produced by the coils is henceforth referred to as the statorfield. The stator field interacts with a rotor consisting of a number ofshorted conductive bars and a structure that is able to rotate around acommon axis with the stator. As the stator field revolves about theaxis, the conductive rotor bars experience a change in magnetic fluxresulting in mechanical rotary motion in the same direction as thestator field. If a shaft is attached to the rotor and supported by anumber of bearings, then the mechanical motion produced on the rotor bythe stator field may be utilized to provide mechanical rotary energy toa system.

An induction generator operates on the same principles as describedabove. However, instead of transforming electrical energy to mechanicalenergy, it transforms mechanical energy into electrical energy. This isachieved by applying a brief excitation current to the stator structure,hence inducing a magnetic field on the rotor structure. If the rotor isthen spun at a speed higher than the motor's synchronous speed, therotary speed determined by the frequency of the machine, then themagnetic field of the rotor will act to induce an electric currentwithin the stator of the motor. This current can then be utilized topower other electric devices.

An axial flux induction motor (AFIM), such as the one illustrated inFIG. 2, refers to a type of induction motor wherein the stator fieldrotates about the axial axis of the motor. One or more stator bodiesproduce a stator field that interacts with a rotor structure (e.g.,bicycle wheel or permanent magnetic to name two). One or more bearingssupport a shaft which is directly attached to the rotor. This designgenerally reduces the overall volume of the motor over radial designs,resulting in higher power densities.

Three phase power operation refers to the utilization of three separatephases with equivalent frequency to produce torque on the rotor and thusrotation. To accomplish this, a number of coils are placed around thestator separated by 360/n (n being the number of coil sets and amultiple of the phases). This coil configuration produces a rotatingmagnetic field (RMF) when three electrical currents with 120 degreephase offset are applied to the coils. Each current is applied to thecoil with the degree separation equivalent to the phase of the current.For example, a base coil, assumed to have a degree of 0, will have apure sine wave current form applied to it. The next coil, assumed tohave a degree of 120 degrees shifted from the base, will have a 120degree phase shifted sine wave applied to it. The final coil, 240 degreeshifted from the base, will have a 240 degree phase shifted sine waveapplied to it. This configuration will produce a smooth RMF that can beutilized for mechanical power production through an electric motor. Asthe number of coil sets in the motor increases, the number of magneticpoles generated during operation increases proportionally. This isdictated by the formula p=(2n)/3, where p is the number of polesgenerated by the coils. Accordingly, a three phase motor comprised ofthree coil sets will produce a two pole rotating magnetic field. Thenumber of poles within the motor is positive and even, as each north orsouth pole generated must also have a complimentary pole generated.These rotating poles interact with a conductive rotor to produce currentwithin the rotor conductors through Faraday's Law of Induction. Theproduced current also produces a magnetic field, which interacts withthe applied current according to Lorentz Force. This interaction willproduce a magnetic force between the applied stator magnetic field andinduced rotor field, thus causing the rotor structure to physicallyrotate and produce mechanical energy.

SUMMARY OF THE DISCLOSURE

The following presents a simplified summary relating to one or moreaspects and/or embodiments disclosed herein. As such, the followingsummary should not be considered an extensive overview relating to allcontemplated aspects and/or embodiments, nor should the followingsummary be regarded to identify key or critical elements relating to allcontemplated aspects and/or embodiments or to delineate the scopeassociated with any particular aspect and/or embodiment. Accordingly,the following summary has the sole purpose to present certain conceptsrelating to one or more aspects and/or embodiments relating to themechanisms disclosed herein in a simplified form to precede the detaileddescription presented below.

Some aspects of the current disclosure can be characterized as an axialflux induction machine comprised of a stator and rotor assembly. Thestator core can be made from material capable of amplifying the magneticfield generated by the coils situated upon it. Such material is oftenreferred to as high permeability material, due to having a high relativepermeability. Two or more stator cores can be utilized in theherein-discussed embodiments. The number of rotors can be adjusted forthe number of stator cores, such that the number of rotors can be oneless than the number of stator cores. Where multiple generators ormotors are combined, the number of rotors can be twice the number ofstators. Other variations on the number of stators and rotors in alsopossible. The stator cores can be comprised of a disk with two rings ofraised surfaces upon which a number of coils are situated. Thesesurfaces may have a lip such as to secure the conductive coils in place(e.g., see FIG. 7), though this lip is not required. The coils may beseparated by a degree determined by the number of phases utilized inoperating the device. The coils can be arranged to overlap therebyproviding a smoother rotating magnetic field and increase efficiency,possibly at the expense of cost, or to remain separate and result incost savings while potentially sacrificing efficiency. The stator mayalso include an outer ring of raised portions upon which the coils canbe wound. This outer ring may include a raised plateau below the coilsas seen in FIG. 7. The inner and outer coils can be wound in opposingdirections, and a single coil may be wound around a raised structure inthe inner ring and a raised structure in the outer ring. The outer ringof raised portions may contact the outer ring of an opposing stator asshown in FIG. 9, while a small gap may be formed between opposing innerrings to leave room for the rotor. The rotor thickness may be minimizedto reduce the air gap between inner rings on opposing stators. At thesame time, this gap should be great enough to resist heat generated. Therotor can be secured to a shaft, and held in place by one or morebearings fitted in centrally located holes on both stators. The assemblymay be held together by a supporting structure designed to prevent thestator plates from slipping apart while not under operation.

Other aspects of the current disclosure may include that the magneticfield of the stator structure can be designed to resemble that of atoroid. The toroid is an efficient electromagnetic shape, and thecombination of upper lip coils and lower coils can work in tandem toproduce a semi-toroidal field. This field may be stronger than that ofrelated electrical machines, resulting in higher output efficienciescompared to similar devices. Due to the outer and inner coilarrangement, the inner coil field can be directed through the outercoils, producing a very tight, semi-toroidal magnetic field. By havinginner and outer rings of coils where the outer ring of one statorcontacts the outer ring of the opposing stator, the magnetic field onlyhas to pass through air gaps between inner rings of opposing stators.Traditional axial motors entails four air gaps that the magnetic fieldpasses through. The reduction in air gap space can result in a moreefficient magnetic field characterized by minimized leakage flux.Furthermore, the inclusion of the outer ring of coils can reduce theoverall size of the axial flux induction machine. Because the upper andlower coils can be configured to experience the same phase and exist onthe same highly permeable surface, the outer coils may be seen as anextension of the inner coils. As such, the overall length of the axialflux induction machine can be reduced when compared to axial fluxinduction machines of similar power output, producing a higher powerdensity while maintaining high efficiency performance.

Other aspects of the current disclosure can be characterized as an axialflux machine that also can act as a generator. After an excitationcurrent is applied such as to produce a magnetic field on the rotor viapreexisting methodologies, the rotor may be spun at above synchronousspeed to produce a voltage across the stator coil windings. This inducedstator voltage can then be fed back into the grid as useable generatedpower. Because of the semi-toroidal shape of the generator stator coils,the magnetic field induced in the stator structures by the rotorstructure may interact with more coils, thus producing higher voltage atthe output. This increased voltage may correspond with higher potentialpower output than traditional axial flux induction machines, thusimproving power density and efficiency. The semi-toroidal shape alsoenables minimization of leakage flux from the generator, producinganother efficiency advantage. This generator offers a number ofadvantages, primarily in the form of improved power density, whichallows for the generator to be installed in smaller enclosures or harderto reach locations (e.g., the wheel of a car or the top of a windturbine).

Some embodiments of the disclosure may be characterized as a fluxinduction machine. The machine can include an axis of rotation, a rotor,a shaft, and a first and second stator. The rotor can be centered aroundand configured to rotate around the axis of rotation. The shaft can passthrough the axis of rotation and couple to the rotor thereby rotatingwhen the rotor rotates. The first and second stators can each becentered around the axis of rotation. Each stator can include an innerand outer ring of high-permeability structures. The outer ring can bearranged further from the axis of rotation than the inner ring. Theinner radius of the outer ring as measured from the axis of rotation canbe greater than an outer radius of the rotor as measured from the axisof rotation. The stators can also include a plurality of conductivecoils each coil wrapped around both: one or more of the structures inthe inner ring; and one or more corresponding structures in the outerring. Further, each coil can have at least two leads accessible from anexterior of the flux induction machine and can be configured forcoupling to an electrical system. Corresponding ones of the outer ringof high-permeability structures between the two stators can be closer toeach other measured axially than corresponding ones of the inner ring ofhigh-permeability structures between the two stators measured axially.

Other embodiments of the disclosure may also be characterized as a fluxinduction machine including an axis of rotation, a rotor, a shaft, andfirst and second stators. The rotor can be centered around andconfigured to rotate around the axis of rotation. The shaft can passthrough the axis of rotation and be coupled to the rotor therebyrotating when the rotor rotates. The first and second stators can becentered around the axis of rotation and can include an inner means forretaining first portions of one or more conductive coils. The statorscan also include an outer means for retaining second portions of the oneor more conductive coils. The outer means can be arranged further fromthe axis of rotation than the inner means. Each of the conductive coilscan be wrapped around both: one or more structures of the inner means;and one or more corresponding structures of the outer means. Each of theone or more conductive coils can have two leads accessible from anexterior of the flux induction machine and configured for coupling to anelectrical system.

Other embodiments of the disclosure can be characterized as a method ofmanufacturing a flux induction machine. The method can include forming arotor and forming a first and second stator. Each stator can include aninner ring of high-permeability structures that extends axially from thefirst or second stator toward the rotor. Each stator can also include anouter ring of high-permeability structures arranged a radial distanceoutside the inner ring, and that extends axially from the first orsecond stator toward the rotor. The method can further include wrappingeach of one or more conductive coils around at least one of thestructures on the inner ring and one of the structures on the outer ringof the first or second stator leaving two leads. The method can furtherinclude wrapping each of one or more conductive coils around at leastone of the structures on the inner ring and one of the structures on theouter ring of the second stator leaving two more leads. The method canfurther include forming a shaft and affixing the rotor to the shaft. Themethod can yet further include rotatably coupling the first stator andthe second stator to the shaft. The leads can be accessible from outsidethe induction flux machine once the rotor and two stators are coupled tothe shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects and advantages and a more complete understanding of thepresent disclosure are apparent and more readily appreciated byreferring to the following detailed description and to the appendedclaims when taken in conjunction with the accompanying drawings:

FIG. 1 shows an example of an electrical coil producing a magneticfield.

FIG. 2 shows an example of a cross-sectional view of a traditional axialflux induction machine with magnetic field lines.

FIG. 3 shows an example of a coil mounting side of a single stator coreof an embodiment of this disclosure.

FIG. 4 shows an example of a three-phase wire configuration for a statorof an axial flux induction machine.

FIG. 5 shows an example of a serial winding connection for four of thecoils of an axial flux induction machine (the additional coils are notshown).

FIG. 6 shows an example of a parallel winding connection for four of thecoils of an axial flux induction machine.

FIG. 7 shows a cross-sectional view of an embodiment of a stator core,with coils, of an axial flux induction machine.

FIG. 8 shows an example of an external side view of a single completedaxial flux induction machine having two stators and one rotor.

FIG. 9 shows an example of a cross-sectional view of a single completedaxial flux induction machine having two stators and one rotor.

FIG. 10 shows the magnetic field lines for the structure of FIG. 9.

FIG. 11 shows an example of a single completed axial flux inductionmachine with sharp edges.

FIG. 12 shows an example of a single completed axial flux inductionmachine with at least some rounded edges.

FIG. 13 shows an example of a rotor and attached shaft.

FIG. 14 shows an example of an external side view of two stacked axialflux induction machine structures with a gap between.

FIG. 15 shows an example of an external side view of a two stacked,abutting axial flux induction machine structures.

FIG. 16 shows an example of a cross-sectional view of a tri-stator axialflux induction machine structure.

FIG. 17 shows an embodiment of an axial flux induction machine havingtwo axial machines stacked on the same shaft along with a traditionalradial induction machine arranged between the two axial flux inductionmachines.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

Preliminary note: the flowcharts and block diagrams in the followingFigures illustrate the architecture, functionality, and operation ofpossible implementations of systems, methods and computer programproducts according to various embodiments of the present invention. Inthis regard, some blocks in these flowcharts or block diagrams mayrepresent a module, segment, or portion of code, which comprises one ormore executable instructions for implementing the specified logicalfunction(s). It should also be noted that, in some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustrations, and combinations ofblocks in the block diagrams and/or flowchart illustrations, can beimplemented by special purpose hardware-based systems that perform thespecified functions or acts, or combinations of special purpose hardwareand computer instructions.

FIG. 3 illustrates one embodiment of the present disclosure with astator that has an inner and outer ring of high-permeability structures.Shown is the coil mounting side of the stator, and in this embodiment,it is configured for three-phase power operation; however, otherembodiments may be configured to accommodate any number of phases by,for example, adjusting the number of coil sets and support structures inthe inner and outer ring. The stator has a core base 302 (see also 702in FIG. 7), that may be formed of a high-permeability material, with acircular cross-sectional area upon which all supporting structuresreside. The circular cross-sectional area may vary in other embodiments.Protruding from the core base 302 is an inner ring of high-permeabilitystructures 304 configured to mount and secure coils (see also 704 inFIG. 7). These wedge-shaped inner ring structures 304 may be adjustedfor a variable number of magnetic poles, power phases, and fieldintensities by, for example, increasing or decreasing the wedge angle orvarying the number of structures 304. Additionally, the protrusionheight and thickness of the inner ring structures 304 can be adjusted toaccommodate different sizes of coils, which may vary according to powerrequirements. Height of a structure 304 is measured vertically in FIG.7. Optionally, the inner ring structures 304 may have an upper lip thatenables them to further secure coils in place. Each inner ring structure304 may provide support for a single coil or a layered coil model.

Optionally, the outer circumference of the core base 302 can include araise structure 306 (see also 706 in FIG. 7), which may have a curved orangled edge. This raised structure 306 may be formed from ahigh-permeability material and may be formed form a unified materialwith the base 302. This raised lip 306 acts as a base for the outer ringof highly-permeable structures 308 and may be used to efficientlytransfer magnetic flux between the coils of the inner ring structures304 and outer ring structures 308; however, in some embodiments thisraised lip 306 may not be present, allowing the outer ring structures308 to rest directly on the core base 302. In such a case, the outercoils and outer ring structures 308 would have a greater height than theinner coils and inner ring structures 304. The outer ring structures 308can protrude from the raised lip 306 and are configured to mount andsecure coils. These outer ring structures 308 may be adjusted for avariable number of magnetic poles and power phases by, for example,varying the number of structures. Additionally, the protrusion heightand thickness of the outer ring structures 308 can be adjusted toaccommodate different sizes of coils, which may vary according to powerrequirements; however, in some embodiments, the outer ring structures308 protrude further than the inner ring structures 304. Optionally, theouter ring structures 308 may have an upper lip that enables them tofurther secure coils in place. The stator has a central hole 307 throughwhich a rotational shaft can pass.

The three-phase power operation of the FIG. 3 embodiment can be achievedusing a wire configuration with overlapping conductive coils such asshown in FIG. 4, although other wire configurations may be used. In FIG.4, the primary coils are separated by 120 degrees, with inverted coilsof equivalent phase separated from a primary coil by 60 degrees. Such adesign would produce a four-pole RMF. The inner conductive coils 404 areall wrapped around the inner ring structures 304, while the outerconductive coils 408 are all wrapped around the outer ring structures308. In an embodiment, one inner conductive coil 404 can be electricallycoupled to one outer conductive coil 408 to form a single conductor. Themagnetic field generated by the inner coils 404 is rotational, equal inphase, and opposite in polarity to the magnetic field generated by theouter coils 408. In other embodiments, the number of coils can vary toachieve a specific number of poles or power phases, and the coils may ormay not overlap.

In some embodiments, an inner coil 404 can be conductively coupled to anouter coil 408 via either a series or parallel connection to form asingle conductive path. The single conductive path may have two leadsaccessible from the axial flux induction machine exterior and beconfigured for coupling to an electrical system (e.g., a power source,battery, the grid, etc).

FIG. 5 illustrates an embodiment of pairs of inner and outer coils beingcoupled in series. FIG. 6 illustrates an embodiment of pairs of innerand outer coils being coupled in parallel. In both cases, the singleconductive path that is formed for all four coils allows multiple coilsto be powered by a single power source, which can then uniformly controlthe power phase of the connected coils.

Referring next to FIG. 7, in some embodiments, the inner coils 714 andthe outer coils 718 can be wound around the inner ring structures 704and the outer ring structures 708 in different configurations to achievedifferent magnetic field paths 720. Shown is a cross-sectional view of asection of a stator with the coil mounting side facing upward. The innercoils 714 are wrapped in the opposite direction of the outer coils 718to achieve the magnetic field path 720, which can be used in formingsemi-toroidal magnetic field loops. In some embodiments, the inner coils714 may be wider than the outer coils 718 to enable the inner coils 714to produce a higher magnetic field density. The inner ring structure 704protrudes from the stator base 702, while the outer ring structure 708protrudes from the raised lip 706, which may have a curved or anglededge. In some embodiments, this raised lip 706 may not be present, andthe outer ring structure 708 may protrude directly from the stator base702. The protrusion height and thickness of the inner ring structure 704and outer ring structure 708 can be adjusted to accommodate differentsizes of coils, which may vary according to power requirements; however,the overall protrusion height of the outer ring structure 708 is greaterthan the protrusion height of the inner ring structure 704 in someembodiments. The inner ring structure 704 and outer ring structure 708have an upper lip that enables them to further secure coils in place,but this lip may not be present in other embodiments. Also, the innerring structure 704 and outer ring structure 708 may provide support fora single coil or a layered coil model. Furthermore, the stator core base702, inner ring structure 704, outer ring structure 708, and raised lip706 may be constructed of one of more high-permeability materials, whichenables the amplification of the magnetic field produced by the innerring coils 714 and outer ring coils 718 while producing the magneticfield path 720.

FIG. 8 illustrates an embodiment of the present disclosure viewed fromthe exterior. Shown is a single completed axial flux induction machinethat contains two stator cores 801 and a rotor (not visible sincecovered by the outer ring coils 818). The outer ring coils 818 of thetwo stator cores 801 are visible along the middle section of the axialflux induction machine exterior. A shaft 809 passes through the axialflux induction machine along an axis of rotation and is configured forrotation.

FIG. 9 illustrates an embodiment of the present disclosure with across-sectional view. Specifically, the interior of a single completedaxial flux induction machine with two stators is shown. The two statorsmay be coupled together at the outer ring and are centered around anaxis of rotation through which a shaft 909 passes. Although not shown,in some embodiments, a gap or short distance may separate the outerrings of the two stators. A rotor 919 is centered around and configuredto rotate about this axis of rotation, and the shaft 909 is coupled tothe rotor 919 to, thereby, rotate when the rotor 919 rotates. Eachstator may be coupled to the shaft via one or more bearings 929, whichmay be constructed of low-permeability material (e.g., ceramic) to avoidmagnetic field interactions that may cause additional friction; however,in other embodiments the stators may not be directly coupled to theshaft. Alternatively, a barrier layer of low-permeability material(e.g., ceramic) can be included between each stator and its respectivebearing. Alternatively, the bearings 929 can be shifted along the shaft909 to separate them from the stators. In some embodiments the shaft 909may be constructed of low-permeability material, avoiding possibleinterference with the axial flux induction machine performance.

In FIG. 9, each stator has an inner ring of high-permeability structures904 and an outer ring of high-permeability structures 908, which arearranged further from the axis of rotation and the shaft 909 than theinner ring of high-permeability structures 904. The inner coils 914 arewrapped around the inner ring structures 904, and the outer coils 918are wrapped around the outer ring structures. The inner ring structures904 protrude from each stator core base 902 toward the rotor and theopposing stator, while the outer ring structures 908 protrude from araised lip 906, which may have a curved or angled edge. In someembodiments, the raised lip 906 may not be present, and the outer ringstructures 908 may protrude directly from each stator core base 902. Theprotrusion height and thickness of the inner ring structures 904 andouter ring structures 908 can be adjusted to accommodate different sizesof coils, which may vary according to power requirements. Space is leftbetween the rotor 919 and the stator structures to enable the rotor torotate without introducing additional friction. The distance, measuredaxially, between the outer ring of high-permeability structures 908 onthe two stators is less than the distance between the inner ring ofhigh-permeability structures 904. In some embodiments, the distancebetween the outer ring of structures 908 may be non-zero but still lessthan the distance between the inner ring of structures 904. In theillustrated embodiment, there is no distance or gap between the outerrings 908. The outer ring structures 908 have an inner radius asmeasured from the rotation axis that is greater than an outer radius ofthe rotor 919. However, in other embodiments where there is a gapbetween the outer ring structures 908 of opposing stators, the outerring structures 908 may have an inner radius that is less than an outerradius of the rotor, but an outer radius that is greater than an outerradius of the rotor.

The inner ring structures 904 and outer ring structures 908 have anupper lip that enables them to further secure coils in place, but thislip may not be present in other embodiments. Also, the inner ringstructures 904 and outer ring structures 908 may each provide supportfor a single coil or a layered coil model. Furthermore, each stator corebase 902, inner ring structure 904, outer ring structure 908, and raisedlip 906 may be constructed of one of more high-permeability materials,which enables the amplification of the magnetic field produced by theinner ring coils 914 and outer ring coils 918 while producing themagnetic field path 920. In some embodiments, the inner coils 904 andouter coils 908 wrapped around corresponding inner ring structures 904and outer ring structures 908 can be conductively coupled, at least oneof in series or in parallel, to form a single conductive path (e.g., seeFIGS. 5 and 6). The single conductive path may have two leads accessiblefrom the axial flux induction machine exterior after assembly therebyenabling coupling to an electrical system such as a power source,battery, transformer, A-D or D-A converter, the grid, etc.

FIG. 10 illustrates an example of a more detailed view of the magneticfield paths of the FIG. 9 embodiment. In some embodiments, the innercoils 1014 and the outer coils 1018 can be wound around the inner ringstructures 1004 and the outer ring structures 1008, respectively indifferent configurations to achieve different magnetic field paths 1020.In some embodiments, the inner coils 1014 may be wider than the outercoils 1018 to enable the inner coils 1014 to produce a higher magneticfield density. The inner coils 1014 can be wrapped in the oppositedirection of the corresponding outer coils 1018 of each stator toachieve the magnetic field path 1020, which can form a semi-toroidalmagnetic field configuration. This semi-toroidal magnetic fieldconfiguration enables the axial flux induction machine to operate moreefficiently with a stronger magnetic field for a given amount of powerthan known axial motors and generators. Additionally, the majority ofthe magnetic field path 1020 may only experience air gaps (e.g., 2) whenpassing between inner ring structures 1014 of opposing stators, whereastraditional axial systems require the field to pass through twice asmany air gaps (e.g., 4). Reducing the number and distance of air thatthe field has to pass through results in a more efficient magnetic fieldcharacterized by minimized leakage flux. The efficiency benefits of theherein-disclosed semi-toroidal magnetic field configuration and thereduced gap space enable the axial flux induction machine to have areduced size for a given operating power.

FIG. 11 illustrates an example of an embodiment of the presentdisclosure where the axial flux induction machine has sharp edges. Shownis a single completed axial flux induction machine that contains twostator cores 1101. A shaft 1109 passes through the axis of rotation andis coupled to the rotor 1119 to thereby rotate when the shaft 1109rotates. The exterior and interior edges of the axial flux inductionmachine are relatively sharp with well-defined corners (e.g., cornershaving small radii of curvature).

In other embodiments, such as the embodiment illustrated in FIG. 12, theedges of the axial flux induction machine may be rounded. FIG. 12 showsa single completed axial flux induction machine that contains two statorcores 1201 and a rotor 1219. A shaft 1209 passes through the axial fluxinduction machine along an axis of rotation and is configured forrotation. A rotor 1219 is centered around and configured to rotate aboutthis axis of rotation, and the shaft 1209 is coupled to the rotor 1219to, thereby, rotate when the rotor 1219 rotates. The exterior andinterior edges of the axial flux induction machine are rounded (e.g.,having a relatively large radii of curvature), which enables the statorcores 1201 to be more aligned with the semi-toroidal magnetic fieldpresent in some embodiments of the present disclosure. Greater alignmentof the stator cores 1201 with the magnetic field may provide greateroverall efficiency of the machine.

FIG. 13 illustrates an example of a rotor that may be used in someembodiments of the present disclosure. The rotor 1319 is centered aroundand configured to rotate about an axis of rotation, and a shaft 1309 iscoupled to the rotor 1319 to, thereby, rotate when the rotor 1319rotates. The rotor 1319 can have two concentric rings, as shown, with aplurality of rotor bars 1303 connecting the inner ring to the outerring. The number and shape of the rotor bars 1303 may vary in otherembodiments. The rotor bars 1303 shown are skewed at a 45 degree anglefrom their center line tangent. In other embodiments, the rotor bars1303 may be skewed at different angles or not at all; however, skewingthe rotor bars 1303 may enable the rotor 1319 to operate moreefficiently. The rotor 1319 may be constructed of one or more conductorsand may also be constructed of one of more high-permeability materials,which enables the amplification of magnetic field intensity. However,one of skill in the art will recognize that other rotor configurations(e.g., permanent magnet) can also be implemented without significantchange to the rotor designs disclosed herein.

In some embodiments, a plurality of axial flux induction machines may bestacked along a single shaft with gaps between each of the axial fluxinduction machines, such as in the embodiment illustrated in FIG. 14 (orwithout gaps as seen in FIG. 15). Stacking without gaps can producehigher efficiency in a smaller volume, but sometimes design stipulationssuggest a preference for gaps. Shown in FIG. 14 is an external view oftwo axial flux induction machines stacked along a single shaft 1409 witha gap between them. Each axial flux induction machine contains twostator cores 1401. The outer ring coils 1418 of each stator core 1401are visible along the middle section of each axial flux inductionmachine exterior. The shaft 1409 passes through the axial flux inductionmachines along an axis of rotation and is configured for rotation. Thecoils of the two axial flux induction machines may be inverted to enablethe production of repulsive magnetic forces between the poles of eachstructure. Such an orientation enables greater magnetic fieldcontainment and reduces the risk of magnetic flux leakage.

In other embodiments, a plurality of axial flux induction machines maybe stacked along a single shaft without a gap between axial fluxinduction machines, such as in the embodiment illustrated in FIG. 15.Shown in FIG. 15 is an external view of two axial flux induction machinestructures stacked along a single shaft 1509. The two axial fluxinduction machine structures are abutting each other with no gap betweenand may contain three stator cores 1501, where abutting stator cores1501 have been merged. In other embodiments, the stator cores 1501 maynot be merged, maintaining the number of stator cores 1501 present priorto stacking. The outer ring coils 1518 of each stator core 1501 arevisible along the middle section of each axial flux induction machineexterior. The shaft 1509 passes through the axial flux inductionmachines along an axis of rotation and is configured for rotation.Although, FIG. 15 only shows two stacked axial flux induction machinestructures, in other embodiments, a greater number of abutting axialflux induction machine structures may be stacked along a single shaft.The stacking of a plurality of axial flux induction machines along asingle shaft allows for scaling into higher power applications that mayexceed the capacity of a single axial flux induction machine. In someembodiments, abutting axial flux induction machine structures can becoupled to form a single structure. An advantage of coupling abuttingaxial flux induction machine structures is that the stator cores of theabutting sides may each be merged into a single stator core, whichshares the magnetic fields of the abutting axial flux inductionmachines. This merging of abutting stator cores enables a reduction ofthe overall number of stator cores, potentially reducing the overallsize of the coupled axial flux induction machines, and enables themagnetic fields of abutting machines to interact more closely, which mayimprove overall efficiency.

Although only two machines are shown in FIGS. 14 and 15, in otherembodiments, three or more stacked machines can be implemented. Further,a traditional radial induction machine can be arranged between any pairof axial induction flux machines as shown in FIG. 17. For instance, oneaxial induction flux machine can be arranged within the wheel or wheelwell of a car on both ends of an axel with a traditional radialinduction machine arranged in a middle of the axel bisecting or roughlybisecting the axel.

As noted earlier, more than two stators and more than one rotor can beimplemented. For instance, FIG. 16 illustrates an embodiment of an axialflux induction machine having three stator cores and two rotors. Thiscross-sectional view may represent an interior of FIG. 15. Along thesesame lines, other embodiments may include any number of stator cores (S)with the number of rotors (R) being one less than the number of statorcores, following the equation R=S−1. The stators may be coupled togetherat the outer ring 1608 and can be centered around an axis of rotationthrough which a shaft 1609 passes; however, in some embodiments, a gapor short distance may separate each of the stators. The rotors 1619 arecentered around and configured to rotate about this axis of rotation,and the rotors 1619 are coupled to the shaft 1609 to, thereby, rotatewhen the rotors 1619 rotate. Each stator may be coupled to the shaft viaone or more bearings 1629, which may be constructed of low-permeablematerial to avoid magnetic field interactions that may cause additionalfriction; however, in other embodiments, the stators may not be directlycoupled to the shaft 1609.

In FIG. 16, the outer two stators are coupled to the shaft 1609 viabearings 1629, while the central stator is not directly coupled to theshaft 1609 and leaves a gap around the shaft 1609. Not directly couplingto the shaft 1609 enables the central stator to reduce the energy lostto friction, increasing the overall efficiency of the axial fluxinduction machine. In other embodiments, this reduction in energy lostto friction becomes magnified as the number of central statorsincreases, making the efficiency increase even more significant (i.e.,regardless of the number of stators, only two need to be coupled to theshaft 1609 via bearings, and in some cases, only a single stator need becoupled to the shaft 1609 via bearings). In some embodiments the shaft1609 may be constructed of low-permeability material, avoiding possibleinterference with the axial flux induction machine performance.

In FIG. 16, each stator has an inner ring of high-permeabilitystructures 1604 and an outer ring of high-permeability structures 1608,which are arranged further from the axis of rotation than the inner ringof high-permeability structures 1604. The high-permeability structuresof the outer stators extend axially towards the central stator, whilethe high-permeability structures of the central stator extend in bothaxial directions towards the outer stators. The inner coils 1614 arewrapped around the inner ring structures 1604, and the outer coils 1618are wrapped around the outer ring structures 1608. The inner ringstructures 1604 protrude from each stator core base 1602, while theouter ring structures 1608 protrude from a raised lip 1606, which mayhave a curved or angled edge. In some embodiments, the raised lip 1606may not be present, and the outer ring structures 1608 may protrudedirectly from each stator core base 1602. The protrusion height andthickness of the inner ring structures 1604 and outer ring structures1608 can be adjusted to accommodate different sizes of coils, which mayvary according to power requirements. Space is left between the innerring structures 1604 to enable the rotors to rotate without contactingthe stators. The distance, measured axially, between the outer ring ofhigh-permeability structures 1608 on adjacent stators is less than thedistance between the inner ring of high-permeability structures 1604 onthe same stators, and in some embodiments the distance between outerring structures 1608 may be zero.

The outer ring structures 1608 have an inner radius as measured from therotation axis that is greater than an outer radius of the rotor 1619.However, in other embodiments where there is a gap between the outerring structures 1608 of opposing stators, the outer ring structures 1608may have an inner radius that is less than an outer radius of the rotor,but an outer radius that is greater than an outer radius of the rotor.

The inner ring structures 1604 and outer ring structures 1608 have anupper lip that enables them to further secure coils in place, but thislip may not be present in other embodiments. Also, the inner ringstructures 1604 and outer ring structures 1608 may each provide supportfor a single coil or a layered coil model. Furthermore, each stator corebase 1602, inner ring structure 1604, outer ring structure 1608, andraised lip 1606 may be constructed of one of more high-permeabilitymaterials, which enables the amplification of the magnetic fieldproduced by the inner ring coils 1614 and outer ring coils 1618 whileproducing the magnetic field path 1620. In some embodiments, the innercoils 1604 and outer coils 1608 wrapped around corresponding inner ringstructures 1604 and outer ring structures 1608 can be conductivelycoupled, at least one of in series or in parallel, to form a singleconductive path. The single conductive path may have two leadsaccessible from the axial flux induction machine exterior, afterassembly, and can be configured for coupling to an electrical systemsuch as a power source, battery, transformer, A-D or D-A converter, thegrid, etc.

In some embodiments, the inner coils 1614 and the outer coils 1618 canbe wound around the inner ring structures 1604 and the outer ringstructures 1608 in different configurations to achieve differentmagnetic field paths 1620. In some embodiments, the inner coils 1614 maybe wider than the outer coils 1618 to enable the inner coils 1614 toproduce a higher magnetic field density. The inner coils 1614 arewrapped in the opposite direction of the corresponding outer coils 1618of each stator to achieve the magnetic field path 1620, which can form asemi-toroidal magnetic field configuration. This semi-toroidal magneticfield configuration enables the axial flux induction machine to operatemore efficiently with a stronger magnetic field for a given amount ofpower. Additionally, a reduced or zero distance between the outer ringstructures 1608 enables a reduction in the gap space that the majorityof the magnetic field path 1620 experiences. This reduction in gap spacecan result in a more efficient magnetic field characterized by minimizedleakage flux. The efficiency benefits of the semi-toroidal magneticfield configuration and the reduced gap space enable the axial fluxinduction machine to have a reduced size for a given operating power.

In some embodiments of the present disclosure, the axial flux machinecan act as at least one of a motor or a generator. When the axial fluxmachine is acting as a motor, electrical current may be provided to thestator coils to produce a RMF, which interacts with the rotor structure,resulting in mechanical rotary motion of the rotor structure and shaft.This mechanical motion of the shaft may be utilized to providemechanical rotary energy to a system. When the axial flux machine isacting as a generator, an excitation current can be applied such as toproduce a magnetic field on the rotor via preexisting methodologies, andthe rotor structure may be spun at above synchronous speed such as toproduce voltage across the stator coil windings. This induced statorvoltage can then be fed back into the grid as useable generated power.Because of the semi-toroidal shape of the generator stator coils, themagnetic field induced in the stator structures by the rotor structuremay interact with more coils, thus producing higher voltage at theoutput. This increased voltage may correspond with higher potentialpower output than traditional axial flux induction machines, thusimproving power density and efficiency. The semi-toroidal shape alsoenables reduced leakage flux from the generator, producing anotherefficiency advantage.

As used herein, the recitation of “at least one of A, B and C” isintended to mean “either A, B, C or any combination of A, B and C.” Theprevious description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the present disclosure.Various modifications to these embodiments will be readily apparent tothose skilled in the art, and the generic principles defined herein maybe applied to other embodiments without departing from the spirit orscope of the disclosure. Thus, the present disclosure is not intended tobe limited to the embodiments shown herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A flux induction machine comprising: an axis ofrotation; a rotor centered around and configured to rotate around theaxis of rotation; a shaft passing through the axis of rotation andcoupled to the rotor thereby rotating when the rotor rotates; a firstand second stator each centered around the axis of rotation, each of thefirst and second stators comprising: an inner ring of high-permeabilitystructures extending axially towards the rotor; and an outer ring ofhigh-permeability structures arranged further from the axis of rotationthan the inner ring and extending axially towards the rotor, wherein aninner radius of the outer ring as measured from the axis of rotation isgreater than an outer radius of the rotor as measured from the axis ofrotation; a plurality of inner conductive coils wrapped around one ormore of the high-permeability structures in the inner ring; and aplurality of outer conductive coils wrapped around one or more of thehigh-permeability structures in the outer ring, wherein a first innerconductive coil of the plurality of inner conductive coils is connectedto a first outer conductive coil of the plurality of outer conductivecoils to form a single conductive path having two leads accessible froman exterior of the flux induction machine and configured for coupling toan electrical system, wherein corresponding ones of the outer ring ofhigh-permeability structures between the two stators are closer to eachother measured axially than corresponding ones of the inner ring ofhigh-permeability structures between the two stators measured axially.2. The flux induction machine of claim 1, wherein the inner and outerrings of high-permeability structures, and their corresponding coils arearranged to form a semi-toroidal magnetic field when current is passingthrough the coils.
 3. The flux induction machine of claim 1, wherein theouter ring of high-permeability structures on the first stator is incontact with the outer ring of high-permeability structures on thesecond stator.
 4. The flux induction machine of claim 1, furthercomprising a third stator and a second rotor, wherein one of the statorsis arranged between the two rotors and has inner and outer rings ofhigh-permeability structures and corresponding conductive coilsextending in both axial directions.
 5. The flux induction machine ofclaim 4, wherein at least two of the stators couple to the shaft viabearings, and wherein another of the three stators is not in contactwith the shaft.
 6. The flux induction machine of claim 1, wherein theflux induction machine is an axial flux induction machine.
 7. The fluxinduction machine of claim 1, wherein the flux induction machine isconfigured to receive power from the electrical system that is thenconverted to rotation of the rotor.
 8. The flux induction machine ofclaim 1, wherein the flux induction machine is configured to convertrotation of the rotor into electricity that is provided to theelectrical system.
 9. The flux induction machine of claim 1, whereineach inner conductive coil is wrapped around two or more of thehigh-permeability structures in the inner ring and each outer conductivecoil is wrapped around two or more of the high-permeability structuresin the outer ring.
 10. A flux induction machine comprising: an axis ofrotation; a rotor centered around and configured to rotate around theaxis of rotation; a shaft passing through the axis of rotation andcoupled to the rotor thereby rotating when the rotor rotates; a firstand second stator each centered around the axis of rotation, each of thefirst and second stators comprising: an inner means for retaining one ormore inner conductive coils; and an outer means for retaining one ormore outer conductive coils, the outer means arranged further from theaxis of rotation than the inner means; and a first inner conductive coilof the one or more of inner conductive coils connected to a first outerconductive coil of the one or more outer conductive coils to form asingle conductive path having two leads accessible from an exterior ofthe flux induction machine and configured for coupling to an electricalsystem.
 11. The flux induction machine of claim 10, wherein the outermeans of the two stators are closer to each other than inner means ofthe two stators.
 12. The flux induction machine of claim 10, wherein theflux induction machine is an axial flux induction machine.
 13. The fluxinduction machine of claim 10, wherein the outer ring ofhigh-permeability structures on the first stator is in contact with theouter ring of high-permeability structures on the second stator.
 14. Theflux induction machine of claim 10, wherein the flux induction machineis configured to receive power from the electrical system that is thenconverted to rotation of the rotor.
 15. The flux induction machine ofclaim 10, wherein the flux induction machine is configured to convertrotation of the rotor into electricity that is provided to theelectrical system.
 16. The flux induction machine of claim 10, whereinan inner radius of the outer means as measured from the axis of rotationis greater than an outer radius of the rotor as measured from the axis.